Panoramic camera and projection systems have been in existence for several decades. The problem of acquiring and displaying panoramic images has been treated extensively over the years and multiple commercial products have been developed based on this concept. Panoramic systems capable of capturing and displaying a 360 degree field of view have applications in entertainment, telepresence (such as virtual reality training scenarios), videoconferencing, and surveillance.
A number of prior art approaches employ complex catadioptric systems with multiple aspherical reflective and refractive optical elements. Examples of such systems may be found with reference to U.S. Pat. Nos. 4,012,126; 4,395,093; and 4,484,801 which include up to twenty-one lens elements in the refracting system, some requiring special glasses, and hyperbolic mirrors in the reflecting system. These imaging systems are typically very expensive to produce due to the large number of custom elements.
A simpler approach to panoramic projection and imaging is described in U.S. Pat. No. 3,240,113. That patent discloses a primary convex mirror formed of a hollow body with an aperture centered about its axis of revolution. The outer surface of the mirror is produced by the rotation of a curved element having its center outside the body axis and intersecting the axis of revolution at an acute angle. A secondary mirror may be a plane, spherical, conical, convex, or revolving mirror which reflects light from the primary mirror toward an objective. This arrangement limits the vertical angle of the 360 degree picture to overcome problems with prior art designs.
Yet another approach to creating a panoramic image is to synthesize frames taken by multiple cameras or by a single camera at successive adjacent intervals. However, a single camera that is scanned introduces undesirable artifacts for moving images while the use of multiple cameras quickly becomes cost prohibitive.
Thus, it is desirable to provide an optical system capable of capturing a wide angle field of view which utilizes relatively few low-cost optical elements while providing a high resolution image.